Study On Agricultural NPS Loads Of Haihe Basin And Assessment On Its Environmental Impact

China is in severe shortage of water resources in terms of per capita amount which is less than 1/3 of the world average. Meanwhile water quality is degrading since the reform and opening up due to swift and vigorous economic development. According to < China's Environmental Aspect Communique 2009>, China's surface water quality was far from satisfactory. The Seven Water Systems were lightly polluted in general, in which Haihe Basin was heavily polluted with 66% of rivers examined less than theâ…¢level of Environmental Quality Standards for Surface Water (GB 3838-2002).Studies have showed that agricultural nonpoint source (NPS) pollution is one of the main contributors to water quality impairments in China. According to < China's First General Survey Communiquéon Pollution Sources > (2009), COD, TN, TP discharged from agricultural sources accounted for 43.7%, 57.2% and 67.4% of national total emissions respectively in 2007.For the first time, this paper studied Haihe Basin agricultural NPS loads and estimate its contribution to water quality. The research findings will help the government to define priority industries and critical areas for water quality control, and to distribute abatement targets between point source (PS) and NPS pollution.This paper set up a new methodology on estimating agricultural NPS loads on macro-scale watershed. It is named as"Three-Dimensional Unit load Method"with following features: (1) The whole basin is divided into smaller units for estimation on three levels---the whole basin, water resource district/ province and county according to river system and landform; (2) Agricultural NPS is divided into three sources---crop farming, animal breeding and rural life; (3) Agricultural NPS is divided into three phases---input, export and deliver to rivers according to polluting formation process.The main findings of this paper are as follows:1.Total Agricultural NPS LoadsIn Haihe Basin in 2007, Agricultural NPS input loads were COD 774.1x10⁴ t, TP 192.0 x10⁴ t, TN 459.1x10⁴ t, NH₄⁺-N 67.8x10⁴ t; export loads were COD 239.4x10⁴ t, TP 4.5x10⁴ t, TN 56.8x10⁴ t, NH₄⁺-N 6.2x10⁴ t; delivered-to-rivers loads were COD 68.0x10⁴ t, TP 0.9 x10⁴ t, TN 8.6x10⁴ t, NH₄⁺-N 1.1x10⁴ t. Tuhaimajiahe Plain/Hebei Province accounted for the largest proportion of agricultural NPS loads in Haihe Basin.2.Contribution of NPS to Water QualityMeasured by multi-year mean amount of surface water resources (1956～2000 hydrologic series), the pollutant loads added to warters by agricultural NPS were COD 31.5 mg·L^-1, TP 0.4 mg·L^-1, TN 4.0 mg·L^-1, NH₄⁺-N 0.5 mg·L^-1 in Haihe Bain in 2007. Compared with theâ…¢level standard of ( GB3838-2002), except for NH₄⁺-N, all others pollutants surpassed the standard by 1.6 times for COD, 2.0 times for TP, 4.0 times for TN.In general, PS contributed the most part of COD (62.0%) and NH₄⁺-N (91.5%), while NPS contributed the most part of TP (60.2%) and TN (58.7%) in river pollution. Based on the fact that only COD and NH₄⁺-N were included in the pollutants list which surpassed the surface water quality standard instead of TP and TN, We would conclude that PS other than NPS was the leading source of river pollution in Haihe Basin.3.Critical Pollutants/Sources/Areas of Agricultural NPSDividing agricultural NPS delivered-to-river loads by theâ…¢level Surface water quality Standard, this paper found that in Haihe Basin (1) TN was the main pollutants contributed by agricultural NPS which accounted for half of the total loads; (2) Agricultural NPS loads mainly derived from livestock waste which accounted for 81% of the total loads; (3) Agricultural NPS loads varied greatly in different regions with Dezhou/ Longhua were the most severely polluted city/county.The government should play a leading role in environmental protection because of the publicity and externality of rural environment while participated widely by the public. Judging the situation in China in environmental protection practices, it was not only insufficient funds or technologies but also poor management including imperfect environmental legal and managerial system that had resulted in ineffective water quality prevention and control. The government should amend current law system to make it more complete and exercisable, strengthen the authority of watershed administrative organization and enhance the coordination and cooperation between all related administrative parties. Meanwhile, the government also needs to expand money input in all kinds of rural eco-friendly activities by ecological compensation and other means of subsidy. The focus of government environmental management and control lies in livestock breeding, which contributes most part of agricultural NPS pollution. In this regard, eco-breeding should be highly encouraged. Meanwhile rural living conditions need to be improved as well."Rural Cleaning Project"is a good choice in building a New Socialist Countryside.